The disclosed embodiments relate to a medical device. Specifically, the disclosed embodiments relate to a catheter that can efficiently transmit a pressing force of an operator to the distal end of the catheter without being bent when being pressed by the operator in the distal direction of the catheter.
Conventionally, catheters are widely used for treating stenoses in blood vessels or alimentary canals. In order to press a catheter to a stenosis, a pressing force applied in the distal direction of the catheter needs to be efficiently transmitted to the end of the catheter.
As a method for such transmission, WO 2006/126642 discloses a catheter having a reinforcing member (core wire) in the longitudinal direction between an outer tube and an inner tube. In the catheter of WO 2006/126642, however, only the reinforcing member is inserted in the longitudinal direction. Unfortunately, this leads to insufficient stiffness, and thus a pressing force applied by an operator in the distal direction is hardly transmitted to the distal end of the catheter.
Japanese Patent Laid-Open No. 2003-164528 discloses a catheter with a metal tube having high stiffness at the proximal end operated by an operator, and a reinforcing member joined to the end of the metal tube. Since the stiff metal tube is provided at the proximal end, a pressing force applied by the operator in the distal direction can be transmitted from the metal tube to the distal end of the catheter through the reinforcing member.
In the catheter of Japanese Patent Laid-Open No. 2003-164528, however, the proximal end of the reinforcing member is joined to the inner peripheral surface of the metal tube, and thus another medical device inserted into the metal tube may be caught at the proximal end of the reinforcing member.
If the proximal end of the reinforcing member is directly joined to the outer peripheral surface of the metal tube to facilitate the insertion of another medical device into the metal tube, the metal tube improves the stiffness of the proximal end and increases the diameter of the outer tube. Unfortunately, this would increase the diameter of the overall catheter so as to prevent the catheter from reaching a site with stenosis on the end of a blood vessel or an alimentary canal. In order not to increase the diameter of the outer tube, the reinforcing member to be inserted into the outer tube needs to be reduced in diameter. Unfortunately, a reduction in the diameter of the reinforcing member would cause insufficient stiffness in the longitudinal direction of the catheter, causing a break on the catheter pressed by an operator in the distal direction.